Studies on the renin-angiotensin-aldosterone system: studies on histological changes in adrenal and renal tissue; a follow-up study of postoperative blood pressure in primary and idiopathic aldosteronism.

Abstract

Adrenalectomy was performed on 20 cases diagnosed as primary aldosteronism on account of their complete conformity to Conn's new criteria and the results of clinical and biochemical examinations. Further, renal biopsy was performed on 15 of them. A single adrenocortical adenoma was found by gross observation in 12 out of the 20 cases (60%). Bilateral adrenocortical hyperplasia was found by pathohistological examination in 7 cases (35%) and in the remaining I case (5%) the adrenal cortex had almost normal appearance. Of the 12 macroscopical adenoma cases, by particular observation, 5 had an almost completely capsulated adenoma; abnormal findings of the renal tissue were not detected in these cases and the postoperative blood pressure recovered completely normal level. As to the other cases that had appeared as an adenoma to the naked eye, it was pathohistological, revealed that adenoma-like mass was continuous to the proper cortex to the adrenal and that hyperplasia was also present in the contralateral adrenal cortex, so these cases were regarded as adenomatous hyperplasia. The postoperative blood pressure was not restored to the normal level except in 3 of them, and sclerotic changes were markedly present in the afferent arteries of the kidney. Of the hyperplasia cases, 4 were found to have micronodular hyperplasia with marked sclerotic changes in the interlobular artery of the kidney, and normal blood pressure was not recovered in these cases except one. The remaining 3 were cases of diffuse hyperplasia; in 2 of them the renal arteries were almost normal and blood pressure was restored to the normal level. Pathohistological findings of the adenoma, adenomatous hyperplasia, and hyperplasia suggest the possibility of transition from hyperplasia to adenoma. It is conceivable that the changes in the renal tissue have a significant influence over the postoperative clinical improvement and normalization of blood pressure, and a part of differential diagnosis between primary aldosteronism and idiopathic aldosteronism.